Too bad there is no way to prepare a default audio track. A lot of older films, expecially a lot of criterion blu rays, have mono audio and stereo commentary tracks. Plex will always pick the stereo commentary track as default no matter what is flagged as default or forced. This gets confusing for a lot of my older relatives as they have to start the movie and then back out to change the audio track once they figure out something is wrong with the audio. You referred to this as a bug here:
Is this still being looked into 2 years later?